9
Figure 2.1 help to explain the seven layers in the OSI model layer. Each layer has its own
network function that will be elaborate one by one in detail below.
2.1.1 Layer 7: Application Layer
Application
layer
is
upper
part
of
the
OSI
model
layer,
very close to user, the main
responsibility to interact with the user application like printing, create database, and
application
service.
Common
applications
that
deal
with
the
application
-
layer
protocol
are
Internet
Mail
Access
Protocol
–
protocol that defines
how
users can access and
store
incoming e-mail messages (IMAP) [6], Trivial File Transfer Protocol – simplified
version
of the TCP/IP file transfer protocol that does not include password protection (TFTP) [6],
HTTP,
Telnet,
SMTP,
FTP,
Post
Office
Protocol version 3
–
an
internet
mail
server
protocol that also provides an incoming mail storage mechanism (POP3) [6], and
Structured Query Language
–
a
query
language
developed
by
IBM
for
use
in
mainframe
application (SQL) [6]. The application layer doesn’t provide services to other OSI layer.
2.1.2 Layer 6: Presentation Layer
The easiest layers that can be understood is the presentation layer its effects can be easily
seen. Main function of this layer to modified the format data send by one system so it can
be readable by another system. It also can translate multiple data formats by using
common
format.
The presentation
layer also can encrypt and decrypt
files
to be readable
by the system, other
function that presentation
layer can do
is
handling
with data
 |